According to a MIMO technology, a multiple-antenna technology is used in a base station and user equipment to suppress channel fading, to significantly increase channel capacity, network coverage, and spectrum utilization. The MIMO technology includes a multi-user multiple-input multiple-output (MU-MIMO) technology and a single user multiple-input multiple-output (SU-MIMO) technology.
According to the MU-MIMO technology, a user equipment (UE) generally feeds back downlink channel information measured by the user equipment to a base station; then, the base station selects, according to a scheduling policy of the base station, appropriate terminals from terminals that need to be served, and performs pairing. Downlink information of successfully paired user equipments can be mapped to different spatial information flows by means of MIMO spatial multiplexing and transmitted on a same communication resource. In a MU-MIMO scenario, the base station uses codebook-based orthogonal pairing. A probability of successful codebook-based orthogonal pairing is very low. If codebook-based orthogonal pairing fails, the base station can schedule only one UE at one time, leading to a waste of radio resources.